Linear actuators are well known and include a variety of configurations. An important requirement in many applications is that the actuator is compact in the axial direction (i.e. total length versus stroke). In order to achieve this, a compact drive mechanism with high force capacity is needed. Some existing drive systems include telescopic features, such as disclosed in U.S. Pat. Nos. 8,286,520 and 8,794,085. Other known types of linear actuators attempt to provide a compact arrangement, but require complex drive mechanisms, such as disclosed in U.S. Pat. No. 6,794,779. Another type of linear actuator requires a gearbox, such as disclosed in U.S. Pat. No. 4,579,012. However, this type of arrangement increases the overall axial length of the assembly, reduces efficiency, and introduces additional failure modes. An additional type of linear actuator is disclosed in U.S. Pat. No. 5,099,161. This type of linear actuator is incapable of handling high loads due to a relatively low mechanical advantage of its ball screw assembly.
It would be desirable to provide a compact and efficient linear actuator drive arrangement that is capable of supporting a high load and is also durable.